The embodiment relates to an elevator controlling method and device, and an elevator using the same. More particularly, the embodiment relates to an elevator controlling method and device, and an elevator using the same that may enhance control performance.
In general, an elevator is used to make people get in and move them up and down in a high-rise building or is used to load and transport cargo. The elevator goes up and down by the driving of a hoist, a kind of a driving device, in an elevator shaft installed in the high-rise building. In addition, an elevator car that has a given space where people may get in or cargo may be loaded is connected and installed to the hoist.
In addition, a 3-phase industrial inverter that generally replaces a DC motor and is used for an elevator driving motor may torque-control an AC motor through vector control.
The brake of an elevator may be controlled by the control of an inverter. When the brake of such an elevator opens, a car shakes, which is called rollback. A load-cell that is a sensor device for measuring the weight is generally used to decrease rollback, and the rollback of an elevator car may decrease using the weight sensing of such a load-cell.
However, a method is being recently developed, which may decrease rollback without load-cell by loading a control algorithm in an inverter itself used for the speed control of an elevator, to increase the reliability matter and the efficiency in speed control of a load-cell sensor.
To decrease rollback, it is important to quickly follow a torque corresponding to the size of a load, which is called load compensation.
FIG. 1 is a diagram for describing an example of a speed controlling device according to the related art to decrease such load compensation.
Referring to FIG. 1, an elevator controlling device, such as P-PI mechanics according to the related art may include a position controlling unit 10, a speed controller 11, a motor speed measuring unit 12, and an inverter 14.
The position controlling unit 10 acquires a position-controlled value θ for controlling a position and an actual positional value θ*, finds the difference between them, multiplies the difference value by a proportional gain value KPP, and outputs a speed-controlled value.
In addition, the speed controller 11 applies proportional gain KP and integral gain KI to the difference between the speed-controlled value and the speed value received from the motor speed measuring unit 12, adds the value, and outputs it as a torque-controlled value T*.
The inverter 14 receives the torque-controlled value a load T1 applied to a motor due to the weight of a car, a rope, passengers, etc. at the elevator, and controls the speed of an elevator. In addition, if an actual speed ω and an actual position θ are measured from the motor controlled by the inverter 14, they may be feedback as the input of the position controlling unit 10 and the speed controller 11.
The inverter 14 makes an actual torque through vector control according to a torque-controlled value and controls speed. The vector control may be performed on current that has been divided into magnetic flux controlling components and torque controlling components. J means an inertia value, S means a Raplace operator, and 1/S means integral.
The transfer function of the elevator controlling device according to the related art is represented by the following Equation 1.
                    θ        =                              s                                          Js                3                            +                                                K                  P                                ⁢                                  s                  2                                            +                                                (                                                            K                      I                                        +                                                                  K                        PP                                            ⁢                                              K                        P                                                                              )                                ⁢                s                            +                                                K                  PP                                ⁢                                  K                  I                                                              ⁢                      T            l                                              〈                  Equation          ⁢                                          ⁢          1                〉            
If designing a pole in case of the elevator controlling device according to the related art, there is a problem that it is difficult to freely arrange the pole. The coefficients of a transfer function are not independent from one another and include the product and sum of gains. Thus, if a gain changes, then two or more coefficients change. As a result, it is not possible to freely design a pole.
In addition, in case of triple root, there is a problem that it is not possible to arrange a pole itself. The reason is that if a discriminant is applied under the assumption of triple root, there is no root value that makes both the discriminant of the cubic equation and the discriminant of the quadratic equation resulting from differentiation of this on the right term in Equation 1 zeros.